New Truck Weighing System

Traditional truck weighing systems assess the gross
weight of the vehicle but cannot tell how the weight is
spread, or if individual axles are overloaded.

Now, an industrial design engineer Dan Rees has
developed a system that indicates the weight being
borne by each axle.

His system, called Load, makes it easier for truck
drivers and operators to avoid the costly fines imposed on overloaded
vehicles, as well as increasing safety and minimising damage to the road.

Rees mounts linear position potentiometers (supplied by Penny & Giles)
on the vehicle using aluminium brackets that allow the sensors to move
through their 50mm stroke without being damaged by road shock.

The system is calibrated in two ways. First, the fully loaded vehicle is
weighed twice a year on an approved weighbridge and when the axle
loads are known, trimming potentiometers are used to map the load
to the sensor travel and vehicle spring rate. The output from each
sensor is equalised using a load distribution display.

Second, whenever the vehicle is empty, the sensors are reset to the
tare position. The tare weight is used as a benchmark because it is
heaviest the vehicle can be when unloaded. It provides a safety factor
against overload because the vehicle is not usually at the maximum
tare weight before being loaded.

The readings from each pair of sensors is compared to find the
largest, which indicates the biggest load the axle can take. This
provides failsafe protection against individual sensor malfunctions.

Dan Rees has been developing his system on a scaled version of
target vehicle -a Leyland DAF truck with a gross vehicle weight of
18 tonnes. It is designed to produce a representative deflection over
both axles and to take advantage of the 50mm stroke of a Penny & Giles
SLS190 sensor.

The system displays individual sensor values and indicates uneven loads.

The Load system is now at the final stage of development before entering
production. Rees is confident that, with further support and investment,
the project will result in a commercial product that is simple to use,
inexpensive reliable and practical.

For more information, please contact:-

Mike Iles at Penny & Giles Controls Ltd. 15 Airfield Road, Christchurch BH23 3TJ. UK
Tel: +44(0)1202-409409  Fax: +44(0) 1202-409475
Email:  Website:

September 2000

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